[IA64] add driver for ACPI methods to call native firmware
[linux-2.6.git] / arch / parisc / lib / checksum.c
1 /*
2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
3  *              operating system.  INET is implemented using the  BSD Socket
4  *              interface as the means of communication with the user level.
5  *
6  *              MIPS specific IP/TCP/UDP checksumming routines
7  *
8  * Authors:     Ralf Baechle, <ralf@waldorf-gmbh.de>
9  *              Lots of code moved from tcp.c and ip.c; see those files
10  *              for more names.
11  *
12  *              This program is free software; you can redistribute it and/or
13  *              modify it under the terms of the GNU General Public License
14  *              as published by the Free Software Foundation; either version
15  *              2 of the License, or (at your option) any later version.
16  *
17  * $Id: checksum.c,v 1.3 1997/12/01 17:57:34 ralf Exp $
18  */
19 #include <linux/module.h>
20 #include <linux/types.h>
21
22 #include <net/checksum.h>
23 #include <asm/byteorder.h>
24 #include <asm/string.h>
25 #include <asm/uaccess.h>
26
27 #define addc(_t,_r)                     \
28         __asm__ __volatile__ (          \
29 "       add             %0, %1, %0\n"   \
30 "       addc            %0, %%r0, %0\n" \
31         : "=r"(_t)                      \
32         : "r"(_r), "0"(_t));
33
34 static inline unsigned short from32to16(unsigned int x)
35 {
36         /* 32 bits --> 16 bits + carry */
37         x = (x & 0xffff) + (x >> 16);
38         /* 16 bits + carry --> 16 bits including carry */
39         x = (x & 0xffff) + (x >> 16);
40         return (unsigned short)x;
41 }
42
43 static inline unsigned int do_csum(const unsigned char * buff, int len)
44 {
45         int odd, count;
46         unsigned int result = 0;
47
48         if (len <= 0)
49                 goto out;
50         odd = 1 & (unsigned long) buff;
51         if (odd) {
52                 result = be16_to_cpu(*buff);
53                 len--;
54                 buff++;
55         }
56         count = len >> 1;               /* nr of 16-bit words.. */
57         if (count) {
58                 if (2 & (unsigned long) buff) {
59                         result += *(unsigned short *) buff;
60                         count--;
61                         len -= 2;
62                         buff += 2;
63                 }
64                 count >>= 1;            /* nr of 32-bit words.. */
65                 if (count) {
66                         while (count >= 4) {
67                                 unsigned int r1, r2, r3, r4;
68                                 r1 = *(unsigned int *)(buff + 0);
69                                 r2 = *(unsigned int *)(buff + 4);
70                                 r3 = *(unsigned int *)(buff + 8);
71                                 r4 = *(unsigned int *)(buff + 12);
72                                 addc(result, r1);
73                                 addc(result, r2);
74                                 addc(result, r3);
75                                 addc(result, r4);
76                                 count -= 4;
77                                 buff += 16;
78                         }
79                         while (count) {
80                                 unsigned int w = *(unsigned int *) buff;
81                                 count--;
82                                 buff += 4;
83                                 addc(result, w);
84                         }
85                         result = (result & 0xffff) + (result >> 16);
86                 }
87                 if (len & 2) {
88                         result += *(unsigned short *) buff;
89                         buff += 2;
90                 }
91         }
92         if (len & 1)
93                 result += le16_to_cpu(*buff);
94         result = from32to16(result);
95         if (odd)
96                 result = swab16(result);
97 out:
98         return result;
99 }
100
101 /*
102  * computes a partial checksum, e.g. for TCP/UDP fragments
103  */
104 /*
105  * why bother folding?
106  */
107 __wsum csum_partial(const void *buff, int len, __wsum sum)
108 {
109         unsigned int result = do_csum(buff, len);
110         addc(result, sum);
111         return (__force __wsum)from32to16(result);
112 }
113
114 EXPORT_SYMBOL(csum_partial);
115
116 /*
117  * copy while checksumming, otherwise like csum_partial
118  */
119 __wsum csum_partial_copy_nocheck(const void *src, void *dst,
120                                        int len, __wsum sum)
121 {
122         /*
123          * It's 2:30 am and I don't feel like doing it real ...
124          * This is lots slower than the real thing (tm)
125          */
126         sum = csum_partial(src, len, sum);
127         memcpy(dst, src, len);
128
129         return sum;
130 }
131 EXPORT_SYMBOL(csum_partial_copy_nocheck);
132
133 /*
134  * Copy from userspace and compute checksum.  If we catch an exception
135  * then zero the rest of the buffer.
136  */
137 __wsum csum_partial_copy_from_user(const void __user *src,
138                                         void *dst, int len,
139                                         __wsum sum, int *err_ptr)
140 {
141         int missing;
142
143         missing = copy_from_user(dst, src, len);
144         if (missing) {
145                 memset(dst + len - missing, 0, missing);
146                 *err_ptr = -EFAULT;
147         }
148                 
149         return csum_partial(dst, len, sum);
150 }
151 EXPORT_SYMBOL(csum_partial_copy_from_user);